Who foots bill when Obama travels?

When President Obama traveled to Florida this week, he sandwiched a partisan speech at Florida Atlantic University between two multimillion-dollar fundraisers for his 2012 campaign, allowing him to label at least part of the trip to a critical battleground state as official business.

While Mr. Obama can rely on Air Force One and other military aircraft at his disposal for official business, federal election laws require his campaign to pay for these presidential perquisites at just a fraction of the cost — the equivalent of a commercial airline ticket — whenever he or other administration officials are using federal government resources for political activity.

Yet, like most of his recent predecessors, Mr. Obama has shown a penchant for piggybacking fundraisers onto official trips, and figuring out the details of how much the Obama campaign must reimburse taxpayers for the mixed trips is complicated and opaque, confounding presidential scholars and even the most experienced federal election law experts.

“Nobody knows how much the travel has to be paid for by either the Democratic National Committee or the president’s campaign committee, or how they come up with the data, or how long they have to reimburse it after the travel takes place,” said Brett Kappel, an expert on election law at Arent Fox. “It’s a total mystery — it’s a black box.”

Brendan Doherty, a political science professor at the U.S. Naval Academy and an authority on presidential fundraising and travel, said he has been unable to figure out the cost of presidential campaign travel for Mr. Obama, as well as presidents that preceded him.